There are many stripping compositions known in the prior art for removing organic coatings from substrates coated therewith. The simplest form of such stripping formulations comprise an aqueous alkaline composition. It is well-known that additional advantages can be obtained by adding various organic components to the alkaline composition in a formulation which is combined to form a single aqueous phase applicable for certain types of coatings. Disclosed in these prior art compositions are such components as tetrahydrofurfuryl alcohol, ethoxylated furfuryl alcohols, ethoxylated alkyl phenols and the like in various combinations. However, such prior stripping compositions are formulated into a single aqueous phase by the addition of coupling agents which assure that the organic solvents are soluble in the aqueous phase.
An example of such single phase aqueous compositions is disclosed in U.S. Pat. No. 3,615,827 to Murphy wherein ethylene glycol monophenyl ether is coupled into solution with an alkaline aqueous solution by the addition of a polyalkylene glycol. Murphy suggests an excess of the organic additives to be used, but only to form a slight oil slick as merely an indicator that the aqueous alkaline solution is saturated with the organic solvent.
In view of the relatively high cost of these organic solvents compared to alkaline components, combining solvents into a single aqueous phase with alkaline components has been considered the most practical and cost effective manner to achieve better stripping action than merely using an aqueous alkaline solution or pure organic solvents by themselves. In many instances, it is typical that these compositions are employed most effectively at elevated temperatures and are referred to as "hot" stripping agents.
Other prior art compositions include components which are less than desirable from an environmental or waste treatment consideration such as phenol, cresylic acid and chlorinated solvents such as suggested by U.S. Pat. No. 3,094,469 to Strauss et al. There has been significant activity over a long period of time searching for a more effective stripping composition, which does not include environmentally hazardous components, to strip organic coatings from substrates in a commercially efficient and more economical manner.